A developing device of an image forming apparatus includes a layer forming member that forms a toner to a fixed layer thickness. A toner in the developing device adheres to a photoreceptor drum to visualize an electrostatic latent image on the photoreceptor drum. The visualized electrostatic latent image is a toner image. The toner image formed on the photoreceptor drum is transferred to a sheet at a predetermined transfer position. The sheet to which the toner image is transferred is heated and pressurized using a fixing device. Thereby, the toner image is fixed to the sheet.
In a case of double-sided printing, an image forming apparatus prints one surface and then prints the other surface. Specifically, in a case of double-sided printing, an image forming apparatus first transfers a toner image to one surface of a sheet and transports the sheet to a fixing device. In addition, when the fixing of one surface is terminated, the image forming apparatus transports the sheet to a transfer position again and transfers the toner image to the other surface.
In a case of double-sided printing, the sheet heated by the fixing device is transported to a transfer position again. For this reason, when double-sided printing is successively performed, the heated sheet warms a transfer unit and a photoreceptor drum, which results in an increase in temperature inside the image forming apparatus. When the temperature inside the image forming apparatus rises, the temperature inside a developing device also rises.
When double-sided printing is successively performed, a toner is stirred inside the developing device in which the temperature rises and transported. Thereby, a toner rotation agent is easily peeled off, or a carrier coating agent is easily peeled off. For this reason, toners tend to stick together.
Thereby, toner sticking such as soft caking and hard caking may occur in a layer forming member. When a toner sticks, the layer forming member cannot form the toner to a fixed layer thickness. For example, the amount of adhering toner is reduced in a portion in which a toner cannot be formed to its original thickness, thereby forming a thin image. For this reason, an image defect such as shading unevenness occurs in the entirety of the formed image.
In addition, once a toner sticks to the layer forming member, the image defect may not be eliminated until the layer forming member is cleaned by, for example, a service man.
In the related art, it may not be possible to prevent an image defect caused by a layer thickness of a toner in advance.